Sensor systems and methods using entangled quantum particles

ABSTRACT

An entangled quantum generator generates a signal including a plurality of entangled quanta. The wavelength of the signal is the sum of the wavelengths of the entangled quanta. A signal processor determines a characteristic of the target based on information derived from at least some of the entangled quanta in the return signal. The frequency of the signal is selected to propagate the signal through a medium and the frequencies of the entangled quanta are selected to provide sufficient data in the return signal to resolve the characteristic of the target.

BACKGROUND

The “Rayleigh diffraction limit”, which is the spatial resolution withwhich an object can be detected, is limited by the wavelength of theradiation used for detection. Higher frequencies are therefore requiredto resolve smaller objects.

Microwaves of high frequency are absorbed in the atmosphere at ratesexponentially higher than microwaves of low frequency. Accordingly, lowfrequency radar is preferred for longer range. However, due to theRayleigh diffraction limit, the ability to distinguish two objectsadjacent to each other, referred to as “resolving power”, isproportional to the ratio of wave length to aperture. As a result, for aunit aperture, radar can only distinguish an object if the wavelength ofthe electromagnetic radiation is the same or smaller than the object.The Rayleigh diffraction limit combined with the earth atmosphere'sattenuation profile forces radar designers to choose between long rangeat low resolution, or short range at high resolution. In an extremeexample, penetrating radars such as foliage penetrating radar (FOPEN) orground penetrating radar (GPR) require low frequencies to minimizeattenuation within the penetrated medium. Consequently, only the verylargest objects can be resolved, diminishing the utility of such radarsystems.

Conventional ocean SOund NAvigation and Ranging (SONAR) sensor systemscan be either passive or active. Passive SONAR is restricted toreceiving signals, while active SONAR both transmits and receivessignals. Active SONAR operates by transmitting a beam of sound wavesthrough water. Sound waves travel faster through water than through air,and more rapidly through salt water than through fresh water. Targetdetection occurs when this beam encounters an object having differentdensity than that of the medium through which the SONAR beam is beingtransmitted (sea water). The beam then bounces off the target and may bedetected by receivers positioned to receive the reflected beam.

Active SONAR is extremely useful in that it gives the exact position ofa target, but it also has some significant drawbacks. Active SONAR isnoisy, and can be easily detected through passive SONAR near theemitting SONAR. Furthermore, the resolution characteristics of activeSONAR do not allow for the exact identification of the target. Inaddition, active SONAR may operate at frequencies over which marine lifeis sensitive.

Ultrasound systems provide images of muscles, tendons, and many internalorgans, their size, structure and any pathological lesions with realtime tomographic images. Ultrasound is commonly used to visualize afetus during routine and emergency prenatal care. Although generallybelieved to be safer than ionizing radiation, some of the known effectsof ultrasonic energy are enhanced inflammatory response and soft tissueheating. Thus, there is some concern that prolonged exposure toultrasonic energy can affect tissue health and development.

According to concepts of quantum mechanics, a quantum system may existin several states simultaneously corresponding to different values of aphysical observable such as position, momentum, or spin. Changes amongproperties of entangled quanta can be correlated. The composite systemis described by a state, that is, a topological structure of substatesdescribing specific observables. Each of these states corresponds toeigenvalues of some set of observables (e.g., quanta positions). Inquantum entanglement, the quantum states of two or more quanta aredescribed with reference to each other, even though the individualobjects may be spatially separated.

SUMMARY

It is thus desirable to provide a sensor system capable of using longwavelengths for propagation range combined with short wavelengths toresolve small objects.

In some embodiments, an entangled quanta generator generates a signalincluding a plurality of entangled quanta. The wavelength of the signalis the sum of the wavelengths of the entangled quanta. A signalprocessor determines a characteristic of the target based on informationderived from at least some of the entangled quanta in the return signal.The frequency of the signal is selected to propagate the signal througha medium and the frequencies of the entangled quanta are selected toprovide sufficient data in the return signal to resolve thecharacteristic of the target.

Other embodiments include generating entangled quanta, transmitting theentangled quanta in a signal. The frequency of the signal is selected topropagate through a particular medium and the number of the entangledquanta is determined by the desired resolution of the return signal. Atleast a portion of the entangled quanta reflected by a target aredetected.

BRIEF DESCRIPTION OF THE FIGURES

Embodiments of the present invention may be better understood, and theirnumerous objects, features, and advantages made apparent to thoseskilled in the art by referencing the accompanying drawings. The use ofthe same reference symbols in different drawings indicates similar oridentical items.

FIG. 1 is a schematic diagram of an embodiment of a quantum sensorsystem;

FIG. 2A shows an embodiment of a photonic module that can be used in awaveform generator in the sensor system of FIG. 1 to generatetopological entangled renormalized quanta;

FIG. 2B is a diagram of an embodiment of an atomic cavity waveformgenerator that can be used in the sensor system of FIG. 1;

FIG. 2C is a diagram showing the energy levels for the atomic cavitywaveform generator of FIG. 2B;

FIG. 3A is a diagram of another embodiment of a waveform generator thatcan be used in the sensor system of FIG. 1;

FIG. 3B is a diagram showing the energy levels for the waveformgenerator of FIG. 3A;

FIG. 3C is a diagram of an alternate embodiment of the waveformgenerator of FIG. 3A;

FIG. 3D is a diagram of an alternate embodiment of the waveformgenerator of FIG. 3A;

FIG. 4 is a diagram of another embodiment of a waveform generator thatcan be used in the sensor system of FIG. 1;

FIG. 5 is a diagram of an embodiment of a series of devices that can beused in the sensor system of FIG. 1 to detect various attributes of theentangled quanta in the return signal;

FIG. 6 is a diagram of an embodiment of a series of devices that can beutilized in the sensor system of FIG. 1 to detect various attributes oftopologically ordered entangled phonons in the return signal;

FIG. 7 is a diagram of an embodiment of a single quantum detector thatcan be utilized in the detector of FIG. 5; and

FIG. 8 is a flow diagram of an embodiment of a process for generating asignal comprising entangled quanta and receiving a return signalcomprising the entangled quanta reflected from a target that can beutilized in the sensor system of FIG. 1.

DETAILED DESCRIPTION

Embodiments of systems and methods for sensor systems using entangledquanta, referred to as quantum sensors, are disclosed herein. Entangledbeams allow the absorption spectrum and the resolution limit of quantumsensor systems to be selected independently of one another. Thus, whileclassical sensor systems such as radar and sonar systems must compromisebetween range and resolution, quantum sensor systems can simultaneouslyachieve the low attenuation/high range associated with a long wavelength and the high resolution associated with a short wave length.

As used herein, the term “quantum sensor system” refers to systems thatuse entangled beams at radio and/or audio frequencies. The terms“quantum” and “quanta” refer to photon(s) for radio frequency wavesand/or phonon(s) for audio frequency waves. The wavelength of two ormore entangled quanta, referred to as a multiquanta, is proportional tothe number of entangled quanta associated with the multiquanta. Forexample, the wavelength of a pair of entangled quanta is twice that ofthe single quanta. The wavelength of three entangled quanta is threetimes that of the single quanta. For a foursome, the difference is amultiple of 4, and so on. It is also possible to entangle two or morequanta of different wave lengths where absorption wavelength of thesignal is the, then, the sum of wavelengths of the constituent quanta.

A measure of performance for classic sensor systems is the signal tonoise (S/N) ratio, which is directly proportional to the frequency ofthe quanta. The higher the frequency, the higher the S/N ratio and,typically, the system performance.

Waves traveling at certain frequencies are absorbed in a medium when thewavelength of propagating quanta is resonant with molecules in themedium, such as water molecules in air. Classical radar systems aretypically limited to microwave frequencies due to absorption, leavingthe far-infrared frequencies largely unused. In classical sonar systems,the most effective propagation waves are often at frequencies that causeharm to marine life that use sonar to detect predators and prey.Entangling quanta into multiquanta changes their resonance behavior and“detunes” them with respect to the absorption bands. Entangled waves cancombine one or more quanta with a relatively high frequency forresolution with one or more quanta at a lower frequency for moreeffective propagation through various absorption bands in theatmosphere, water, or other medium. The frequencies of the waves forpropagation and resolution can be separately controlled, allowing thequantum sensor system to use signals for resolution at previously unusedor less harmful frequencies. Thus, quantum sensor systems are typicallycapable of providing information about targets that cannot be providedusing classical sensor systems.

In classical sensor systems, return signal energy is proportional to thedensity of radiation power emanating from the antenna (P_(avg)),spectral cross-section of the target (σ), area of aperture (A_(eqv))(assuming receive and transmit antennas are the same size), and time ontarget (t_(tot)); and is inversely proportional to the distance to thetarget (R), the wavelength of the signal (λ), and a loss factor (L), asshown by the following equation:

${{Signal}\mspace{14mu}{Energy}} = \frac{P_{avg}A_{eqv}^{1}\sigma\; t_{tot}}{4\pi\; R^{4}\lambda^{2}L}$To determine the return signal energy for a quantum sensor system, let cdenote the speed of light, h denote Planck's constant, E_(ef) denote theenergy per entangled quanta of frequency ω_(ef), N_(efPmf) the number ofentangled quanta per multiquanta, and N_(mf) the number of multiquantaper second. The wavelength associated with the entangled quanta isdetermined using the deBroglie equation:

$\lambda_{ef} = \frac{h\; c}{N_{efPmf}E_{ef}}$E_(ef) = h ω_(ef) = h c/λ_(ef) P_(avg) = E_(ef)N_(efPmf)N_(mf)/t_(tot)then substituting the above terms into the classical radar/sonar signalenergy equation, the signal energy for a quantum sensor system is givenby:

${{Signal}\mspace{14mu}{Energy}_{QR}} = {\frac{hc}{4\pi}{N_{mf}( \frac{A_{eqv}^{2}\sigma}{R^{4}L} )}( \frac{N_{efPnf}}{\lambda_{ef}} )^{3}}$Thus, the signal energy of a sensor system using entangled quanta isproportional to the cube of the number of entanglement quanta permultiquanta. Note that the effective wavelength λ_(ef) is inverselyproportional to the number of entangled quanta in a multiquanta. As aresult, the return signals from the individual quanta can be used toachieve high target resolution while the wavelength of the multiquantacan be designed for effective propagation through the subject medium.

Range resolution in conventional sensor systems is inverselyproportional to the pulse width of the waveform generator signal. Onetechnique to improve resolution despite the Rayleigh limit is referredto as “pulse compression”, which compresses a long pulse temporallywhile maintaining the total energy of the pulse. Increased resolution isachieved at a cost of less image data per unit time.

Another technique to improve resolution despite the Rayleigh limitincludes increasing the length scale of the aperture by using traveldistance over a period of time to create a “synthetic” aperture.Synthetic Aperture Radar (SAR) systems increase resolution at the costof extending the time required to collect an image. As a result, areduced number of images can be collected in a given interval.

While increasing resolution in quantum sensor systems requires anincrease in energy per pulse, the penalty of longer exposure time is notincurred, as in classical sensor systems that use techniques such aspulse compression and synthetic aperture. In military systems, longerexposure time increases the risk of the signal being detected. Note,however, that the time on target t_(tot) cancels out of the signalenergy equation for quantum sensor systems, offering the advantages ofhigh resolution, with lower probability of the signal being detected intactical situations, compared to classical sensor systems. According tothe radar/sonar equation, a quantum sensor system can focus more energyon the target per unit of aperture per unit time and extract moreinformation than a comparable classical sensor system.

One limitation in classical sensor systems is that the ratio of imagingrate to resolution is fixed such that searching for and tracking targetscannot be accomplished simultaneously. Different sensor systems, orcomplex sensor systems capable of operating in interleaved modes, arerequired to detect ground, air, and underwater moving targets. Withquantum sensor systems, however, the imaging rate to resolution ratiocan be selected for simultaneous targeting, tracking, and syntheticaperture imaging. Additionally, multiquanta in multiple frequency rangescan be generated dynamically to propagate through different mediums andresolve different types of targets.

Referring to FIG. 1, a diagram of an embodiment of quantum sensor system100 is shown including transmitter section 102 with entangled quantumwaveform generator 104 that emits sensor beams comprising entangledmultiquanta waveforms. Quantum waveform generator 104 can furtherarrange the entangled quanta in topological orders to help prevent theentangled multiquanta waveforms from decohering as the waveforms arepropagated to a medium, reflected off a target, and detected andprocessed by system 100. Further, entanglement renormalization can beused to obtain an effective description for topological states.

Topology refers to mathematical properties that are unchanged when anobject is smoothly deformed. Topological ordering refers to usingquasi-particles to represent quanta as the quanta move through time andspace. The quasi-particles are referred to as anyons. Pairs of adjacentanyons may be moved around one another in a determined sequence to forma thread. With multiple threads, the pairs of anyons can be swapped toproduce a braid of all the threads. The final states of the anyons areencapsulated in the braid and are protected from outside disturbancesand interference, i.e., decoherence. Non-abelian anyons are typicallyused so that final states of the anyons depend on the order in which theanyons are swapped. The transformation from one state to another can berepresented by a matrix. Different transformations can be used torepresent different information and used to encode and decode theinformation in the anyon braid.

Renormalization group (RG) transformations can be used to obtain aneffective description of the large distance behavior of extendedsystems. In the case of a system defined on a lattice, this can beachieved by constructing a sequence of increasingly coarse-grainedlattices, where a single site of lattice effectively describes a blockof an increasingly large number of sites in the original lattice.Entanglement renormalization is a RG transformation that usesdisentanglers prior to the coarse-graining step to reduce the amount ofentanglement in the system. When applied to a large class of groundstates in both one and two spatial dimensions, a steady dimension ismade possible by the disentangling step. The resulting RG transformationcan be iterated indefinitely at a constant computational cost, allowingfor the exploration of arbitrarily large length scales. In addition, thesystem can be compared with itself at different length scales, and thusRG flows can be studied in the space of ground state or Hamiltoniancouplings. A constant dimension also leads to an efficientrepresentation of the system's ground state in terms of a tensornetwork, which is referred to as the multi-scale entanglementrenormalization ansatz (MERA).

In some embodiments, signals are both transmitted and received viaantenna 106. In such embodiments, duplexer 108 switches to provide theoutput of waveform generator 104 to antenna 106 during transmit mode.Note that in other embodiments, different and/or multiple antennas 106can be used for transmit and receive functions.

Receiver section 110 typically includes detector 112, signal qualityprocessor 116, and signal/data processor 120. The sensor data generatedby processor 120 as images and/or other suitable format can be providedto display 122 as well as other output devices such as a printer orstorage media. Waveform generator 104 and signal/data processor 120interface with controller 124. Controller 124 can provide signals topositioning system 130, which adjusts the direction in which radar beamsare transmitted and received to provide improved information regarding atarget.

Waveform generator 104 can be configured to generate single quantaand/or multiquanta waveforms using a variety of different techniques anddevices such as one or more photonic modules, atom cavities, quantumdots, Bose-Einstein condensates as well as other suitable devices forgenerating entangled quanta. One approach to quantum waveform generationinvolves entangling one degree of freedom of the quanta such as a spin.If a disturbance in the environment changes the state of the quanta, thewaveform may become decoherent.

Topological ordering can be used in waveform generator 104 to stabilizethe quantum waveform. A topological waveform generator 104 can encodeinformation in configurations of different braids, which are similar toknots but consist of several different threads intertwined around eachother. By encoding waveforms in braids instead of single particles, atopological quantum waveform generator encodes the quanta in phaserelations. Further, the waveform can be represented redundantly so thaterrors can be diagnosed and corrected if the phase relations aredisrupted during propagation and/or processing. Further, entanglementrenormalization transformations can be used to reduce the amount ofentanglement in the waveforms. See the techniques discussed, forexample, in “Entanglement Renormalization and Topological Order” byMiguel Aguado and Guifre Vidal, arXiv:0712.0348v2 [cond-mat.str-el] 21Feb. 2008, which is incorporated by reference herein. Note that althoughthe preceding publication discusses techniques for abelian quanta,nonabelian quanta can also be used in waveform generator 104. The term“abelian” refers to quanta that have commutative properties, whereas“nonabelian” quanta are not commutative. Abelian quanta have commutativeproperties, while non-abelian quanta do not. In quantum mechanics,commutative means that the outcome is independent of the order ofoperations. For example, consider two operators, A and B, which changethe system in some way (translation, rotation, propagation through time,etc.) If these operators commute with one another,AB|system>=BA|system>. If they do not commute, AB|system>does not equalBA|system>: that is, the outcome of the operations is dependent upon theorder in which the operations is performed. If quanta have commutativeproperties, the outcome of operations performed on them is irrespectiveof the order of operations, whereas if they do not have commutativeproperties, the order of operations does matter.

FIG. 2A shows an embodiment of photonic module 200 that can be used inwaveform generator 104 to generate topological entangled renormalizedquanta. Photonic module 200 can include an atom cavity system 202,polarizing beam splitters (PBS) 204, 206, optical delays 208, 210, andhalf wave plates (HWP) 212, 214 and is described in detail in “ThePhotonic Module: an on-demand resource for photonic entanglement” bySimon J. Devitt et al., arXiv:0706.2226v2 [quant-ph] 12 Oct. 2007, whichis incorporated by reference herein. Control lasers 216 provide a singlephoton source, which can produce a train of single photon pulses ofknown polarization, separated by a specified time interval. Cavity 202generates two photons that are routed through components in photonicmodule 200 as a result of the excitation by lasers 216.

For a single photon passing through the module, the natural operation ofthe module, M, is given by,M|+

^(I)|φ

→|+

^(O)|φ

,M|−

^(I)|φ

→|−

^(O)|φ

.  (Equation 1)Where |±

=(|H

±|V

)/√2, |φ

=α|0

+β|1

is the state of the atomic qubit, |φ

=X|φ

=α|1

+β|0

and indices {I,O} represent input and output optical modes. Cavitysystem 202 is positioned such that the cavity mode is coupled to aspatial mode |o

^(B2), where o denotes the photon polarization and cavity Q-switching(which allows for the adiabatic loading of a single photon into acavity) is employed before and after the atom/photon interaction toensure appropriate in- and out-coupling to and from the cavity system202. The mode |o

^(B1) contains an optical delay 210 equal to the time required for thephoton/atom interaction. A single photon passing through the atom/cavitysystem 202 induces a photonic non-demolition bit-flip on the two-levelatom, releasing the photon again into |o

^(B2) once the interaction is complete.

If the photonic state is |+

, HWP 210 rotates the state to |H

after which it will continue into the mode |o

^(B1) and not interact with the atom. The second PBS 204 and HWP 208will then couple |o

^(B1) to the output mode and rotate |H

back to |+

. If the initial photonic state is |−

, the HWP 208 will rotate the state to |V

and the PBS 204 will reflect the photon into the |o

^(B2) mode, where it flips the state of the atomic qubit. The photon isthen released back into |o

^(B2) where the second PBS 204 and HWP 208 reflect the photon into theoutput mode and rotate it from |V

to |−

. Therefore, the two basis states, |±

, of a single photon passing through the module will enact thetransformation M shown in Equation 1 above.

For a two photon train, the output pulse consists of the original twophoton train which is polarization entangled into a two photon Bellstate. The measurement result of the atom/cavity system 202 does notcollapse the photons to unentangled states.

FIG. 2B shows an embodiment of atom cavity 250 in which one or moreenergy beams 252 are directed to one or more atoms trapped in anenclosed cavity 256 formed by a field between two superconductingmirrors 258. One or more devices 260 capable of generating an energybeam 252, such as a laser, maser, ultrasonic, and/or any other type ofenergy beams, can be used to accelerate or decelerate electrons in atomsin cavity 256, thereby generating a signal 262 composed of multipleentangled quanta. Controller 124 can be configured to control operationof energy beam device 260 to generate entangled quanta at thefrequencies desired to detect one or more characteristics of a target.

An example of an atom cavity 256 capable of generating multipleentangled quanta is described in “Step-by-Step Engineered MultiparticleEntanglement” by Arno Rauschenbeutel, Gilles Nogues, Stefano Osnaghi,Patrice Bertet, Michel Brune, Jean-Michel Raimond, and Serge Haroche,Science Magazine, Vol. 288, Jun. 16, 2000, (hereafter referred to as“Rauschenbeutel” and incorporated by reference herein). FIG. 2C showsthe relevant atomic levels e, g, and i of atoms in cavity 256. Atomsemitted by energy beam devices 260 are prepared in e or g atomic levels.The atoms cross cavity 256 resonant at frequency C on the e→gtransition. Classical Rabi pulses at frequency S from pulse generator264 can be applied on the atoms before and after they interact withcavity 256 to perform programmed transformations on each atomic state.The term Rabi pulses refers to an atom that cyclically absorbs andre-emits quanta at resonance when illuminated by a coherent beam ofquanta.

A static electric field applied across mirrors 258 is used to controlthe atomic transition frequency through the Stark effect, which refersto the shift in, and broadening of, the spectral line structure ofmatter in the presence of an electric field. The residual quantum numberincreases at the end of the sequence. The position of an atom can bedetermined with a precision that allows each atom to be addressedindependently. The joint atom-quantum state manipulations rely on theresonant quantum Rabi rotation experienced by each atom in cavity 256.Atom cavity system 250 undergoes oscillations between the states |e,0

and |g,1

(atom in e or g with either zero or one quanta). The full effective atomcavity interaction time corresponds to a 2π Rabi pulse. Shorterinteraction times are obtained by using the Stark effect to switch theatomic transition away from cavity resonance at preset times. Anentangled state is achieved by combining Rabi pulses of variousdurations on successive atoms.

Referring now to FIGS. 3A and 3B, another embodiment of a waveformgenerator 300 configured to generate multiquanta waveforms using quantumdots (A, B, L, R) that can be used in sensor system 100 is shown.Quantum Dots (QDs) are very small semiconductor structures on the orderof nanometers or somewhat larger in diameter that confine electrons andholes in three spatial dimensions and to a very small number of energylevels, depending on their size. A QD is larger than an atom but behavesas if it were one, releasing its trapped electron-hole pair to anadjacent conductor when it captures an incident quantum.

A publication entitled “Entangled Microwaves From Quantum Dots” by C.Emary, B. Trauzettel, and C. W. J. Beenakker, Instituut-Lorentz,Universiteit Leiden, P.O. Box 9506, 2300 RA Leiden, The Netherlands,(Feb. 23, 2005) (referred to herein as “Emary” and incorporated byreference herein) discloses examples of techniques for producingpolarization-entangled microwaves using intra-band transitions in a pairof quantum dots. The techniques do not rely on spin-orbit coupling or oncontrol over electron-electron interactions. The quantum correlation ofmicrowave polarizations is obtained from orbital degrees of freedom inan external magnetic field.

FIG. 3A shows four quantum dots A, B, L, R, arranged between twoelectron reservoirs 302. In the embodiment shown, quantum dot L iscoupled to one of electron reservoirs 302 and quantum dots A and B, asdiscussed in Emary. Quantum dot R is coupled to the other electronreservoir 302 as well as quantum dots A and B. There is no directcoupling between quantum dots L and R, or A and B.

FIG. 3B shows the positions of quantum dot levels for quantum dots A, B,L, R. An electron tunnels through the single level in dot L into asuperposition α|A*

+β|B*

of upper levels in dots A and B. The electron decays to the ground statewith the emission of two quanta. The resulting state α|A_(g)

|++

β|B_(g)

|−−

encodes the state of the quantum dot L onto pairs of quanta with left orright circular polarization. Subsequent tunneling of the electron out ofthe lower levels into quantum dot R establishes a unique final state forthe electron, thus separating the quantum dot field wave function andliberating a pair of entangled quanta 304, 306.

FIG. 3C shows another embodiment of a waveform generator 310 configuredto generate multiquanta waveforms using only two dots, with dots L and Rbeing replaced by Y-junction connections. The quantum dots A and B areconnected to within a Fermi wavelength of each other at the Y-junctionsto ensure that an electron tunnels coherently into both quantum dots Aand B, as further described in Emary.

Another publication entitled “Creating Excitonic Entanglement In QuantumDots Through The Optical Stark Effect” by Ahsan Nazir, Brendon W.Lovett, and G. Andrew D. Briggs, Department of Materials, OxfordUniversity, Oxford OX1 3PH, United Kingdom, Nov. 3, 2004, andincorporated by reference herein, discloses that two initiallynon-resonant quantum dots may be brought into resonance by theapplication of a single detuned laser. In some systems, such as anembodiment of system 320 shown in FIG. 3D, one laser 322 can be used totrigger or generate the quanta, and another laser 324 can be used tocouple the emitted quanta in an entangled RF wave 326. Note that someembodiments can include an array 328 of quantum dots and triggering andcoupling lasers 322, 324. A corresponding number of additional lasers322, 324 can be used to generate more than two entangled quanta.

Referring now to FIG. 4, another embodiment of waveform generator 400configured to generate multiquanta waveforms 402 using Bose-Einsteincondensates (BECS) 404 that can be used in sensor system 100 is shown.BECs 404 are comprised of a group of atoms that exist in exactly thesame state. Methods to produce entangled states of several quanta from aBEC 404 are described in “Many-Particle Entanglement With Bose-EinsteinCondensates” by A. Sørensen, L.-M. Duan, J. I. Cirac & P. Zoll, Nature409, 63 (2001), incorporated by reference herein, using atom-atominteractions and/or spin-exchange collisions to create entangled quantain multiquanta waveforms 402. The publication “Creating MassiveEntanglement of Bose-Einstein Condensed Atoms” by Kristian Helmerson andLi You, Physical Review Letters, Volume 87, Number 17, Oct. 22, 2001,incorporated by reference herein, further proposes using a Raman processthat couples the atoms through intermediate molecular states to entanglea large number of quanta.

Note that other suitable methods for generating multiquanta waveformscan be used in sensor system 100 in addition to, or instead of BECs 404,quantum dot systems 300, and atom cavity systems 200.

Referring again to FIG. 1, controller 124 can be configured to perform amodulating function by controlling a laser or other energy source inwaveform generator 104 to transmit pulsed or continuous multiquantawaveforms. Additionally, waveform generator 104 can be controlled tovary one or more properties of successive entangled quantum waveforms sothat either or both the frequency and the property of interest can bedetected to correlate emitted and return signals.

Positioning system 130 can be operated by controller 124 in coordinationwith waveform generator 104 to achieve desired sensor beam shapes and tofocus the emitted signal in a particular direction. The desired sensorbeam shapes can be indicated by an automatically and/or manuallyactuated sensor mode switch coupled to provide input to controller 124.

Referring now to FIGS. 1 and 5, FIG. 5 shows an embodiment ofdownconverter 500 that can be used in sensor system 100 in which thewaveforms are not topologically ordered. The return signal is comprisedof multiple entangled quanta, which are separated by a series of beamsplitters 502. Since measuring an attribute of an entangled photonalters the attribute, the number splitters 502 included in detectorsystem 500 depends on the number of attributes of the entangled quantato be measured. In the embodiment shown, quanta deflected by the seriesof splitters 502 are input to corresponding attribute-specific detectiondevices 512, such as polarizing filter 504, spin detection device 508,and interferometer/spectrometer 510.

Polarizing filter 504 indicates the polarization of the quanta in thereturn signal and can be used to determine the direction of a target'svelocity vector. Spin detection device 508, such as a Stem-Gerlachdevice, indicates the spin of the quanta in the return signal. The levelof spin can be used to determine the magnitude of the target's velocityvector. Measurements from interferometer/spectrometer 510 can be used todetermine the phase and analyze spectral properties of the quanta in thereturn signal. The phase angle can be used to determine azimuth andelevation of the target, as well as the Doppler shift of the returnsignal. Spectral analysis can be used to determine the materialcomposition of the target. Other devices suitable to measure specificattributes of the quanta in the return signal can be used. Such aconfiguration allows entangled quanta to be separated and attributes tobe measured independently of one another, that is, without affectingother attributes of the entangled quanta.

A quanta detector 506 can be included with each attribute-specificdetection device 512 to count the number of quanta with the detectedattribute. The detected number can be used to determine a statisticalestimate of the number of quanta in the return signal with that specificattribute. A schematic diagram representing an example of detector 506capable of detecting single quantum is shown in FIG. 7 and described ina publication entitled “Demonstration Of A Low-Noise Near-InfraredPhoton Counter With Multi-photon Discrimination,” by Aaron J. Miller,Sae Woo Nam, John M. Martinis, and Alexander V. Sergienko, AppliedPhysics Letters, Volume 83, Number 4 (Jul. 28, 2003) and incorporated byreference herein. Note that detector 506 can be configured with amicrophone to detect phonons instead of photons.

Detector 506 includes a superconducting absorbing material 702 that usestransition edge sensor (TES) microcalorimeter technology to produce anelectrical signal proportional to the heat produced by the absorption ofa quantum from the return signal. Absorbing material 702 can beconfigured as a metal film, such as tungsten, with very narrowsuperconducting-to-normal resistive transition characteristics. Applyinga voltage across the metal film causes the film to self-bias in theresistive transition allowing its temperature to be determined bymeasuring the electrical current flow through the metal. The integral ofthe current pulse is proportional to the energy deposited in theabsorbing material 702 from the quantum in the return signal. Thevoltage bias for detector 506 is provided by current source (I_(bias))and a shunt resistor (R_(b)). The detector signal I_(sense) is amplifiedby one or more amplifiers 704, such as an array of SQUID amplifiers, andprocessed with pulse shaping electronics 706. Note that other suitabletypes of detectors 506 can be used.

Referring now to FIGS. 1 and 6, FIG. 6 shows a diagram of an embodimentof a detector system 600 that can be used as detector 112 in sensorsystem 100 that uses waveforms with topological ordering andentanglement renormalization transformations. The return signal iscomprised of multiple entangled quanta, which are separated by a seriesof beam splitters 602. Since measuring an attribute of an entangledquanta alters the attribute, the number splitters 602 included indetector system 600 depends on the number of attributes of the entangledquanta to be measured. In the embodiment shown, quanta deflected by theseries of splitters 602 are input to corresponding attribute-specificdetection devices 612, such as one or more topological interferometers604, 608, and interferometer/spectrometer 610.

Interferometric topological 604, 608 are configured to measure or detectattributes of entangled quanta in topological order with entanglementrenormalization. In some embodiments, interferometric topological 604,608 include an interferometer with a fractional control module that isused to adjust a mirror capable to control the length of the waveformpath within the interferometer within nanometers. Interferometrictopological 604, 608 thus can be used as a modulator that is configuredto decoding sequences of waveforms according to an attractor and ascale. The attractor can be used to analyze frequencies and signalattributes or sequences, namely the waveform alphabet's sequence andfrequencies. The attractors are mapped to each element or sub-element ofthe frequency, frequency distribution, waveform, signal attribute orsequence, thereby forming a sequence of symbols that can be eitherinverted back to the original frequency, frequency distribution,waveform, signal attribute or sequence or used for detection,recognition, characterization, identification or description offrequency, frequency distribution, waveform, signal attribute, sequenceelement or sequence.

Measurements from interferometer/spectrometer 610 can be used todetermine the phase and analyze spectral properties of the quanta in thereturn signal. The phase angle can be used to determine azimuth andelevation of the target, as well as the Doppler shift of the returnsignal. Spectral analysis can be used to determine the materialcomposition of the target. Other devices suitable to measure specificattributes of the quanta in the return signal can be used. Such aconfiguration allows entangled quanta to be separated and attributes tobe measured independently of one another, that is, without affectingother attributes of the entangled quanta.

A quanta detector 506 can be included with each attribute-specificdetection device 612 to count the number of quanta with the detectedattribute. The detected number can be used to determine a statisticalestimate of the number of quanta in the return signal with that specificattribute. A schematic diagram representing an example of detector 506capable of detecting single quantum is shown in FIG. 7 and described ina publication entitled “Demonstration Of A Low-Noise Near-infraredPhoton Counter With Multi-photon Discrimination,” by Aaron J. Miller,Sae Woo Nam, John M. Martinis, and Alexander V. Sergienko, AppliedPhysics Letters, Volume 83, Number 4 (Jul. 28, 2003) and incorporated byreference herein.

Referring again to FIG. 1, the information available fromattribute-specific detection devices 512, 612 (FIGS. 5, 6) can beprovided to signal quality processor 116. Signal quality processor 116can filter noise out of the signals, and perform other functions tocondition the signals to provide the most information available tosignal data processor 120. In some embodiments, signal quality processor116 can measure the fidelity of the return signal and distinguish thereturn signal from noise using a lattice or other suitable structure.

Signal/data processor 120 coherently combines the pulses within eachreturn signal to obtain a sharpened image that can be presented ondisplay 122. Image analysis logic can be included in signal processor120 to determine the type of target(s) shown in the image, as well as todetermine speed, direction, number, and other attributes of thetarget(s).

Components in processing system 100 can be embodied in any suitabledevice(s) using any suitable combination of firmware, software, and/orhardware, such as microprocessors, Field Programmable Gate Arrays(FPGAs), Application Specific Integrated Circuit (ASICs), quantumcomputers, or other suitable devices.

The ability to propagate sensor signals at frequencies that areindependent of the resolution frequency may allow quantum sensor system100 to attain near zero attenuation rates in the propagation medium, andgreatly diminished attenuation rates in other media including foliage,building materials, earthen layers, etc. Quantum sensor system 100,thus, can be adapted to visualize useful target details throughbackground and/or camouflaging clutter, through plasma shrouds aroundhypersonic air vehicles, through the layers of concealment hidingunderground facilities, IEDs, mines, and other threats—all whileoperating from an airborne, waterborne, or other suitable platform.Quantum sensor system 100 may also improve the performance of advancedimage processing and pattern recognition systems, as well as defeat mostsignature management systems when the propagation frequency is tuned tothe resonant wave length of the target.

FIG. 8 is a flow diagram of an embodiment of a process for generating asignal comprising entangled quanta and receiving a return signalcomprising the entangled quanta reflected from a target that can beutilized in the sensor system 100 of FIG. 1. Process 800 can includedetermining one or more characteristics of target(s) to be detected. Thecharacteristics can include distance, azimuth and elevation, materialcomposition, type of target, high/medium/low resolution images,traveling speed and direction, and other suitable characteristics. Oneor more mode selection switches can be provided for an operator todynamically select one or more of the characteristics to be detected.Further, components in sensor system 100 such as controller 124 can beconfigured to automatically add and/or switch modes based on theoperating mode(s) of other devices, such as aircraft, watercraft, spaceplatform, or other device, with which sensor system 100 can be utilized.

Process 802 can include determining wavelength/frequency for theentangled quanta based on characteristic(s) to be detected. For example,if detailed images of the target(s) are desired, process 802 determinesa suitable wavelength and corresponding frequency for the quanta basedon the characteristic to be detected. The desired frequency/wavelengthcan be adjusted automatically based on operational mode of the sensorsystem 100.

Different frequencies can be used for different propagation mediums suchas air, water, vacuum, foliage, ground, and buildings. Process 804includes generating the entangled quanta(s) at the desired propagationfrequency once the propagation medium is provided or determined. Forexample the propagation medium can be provided manually through operatorinput or determined automatically based on sensor data and/or imageanalysis. Various types of sensors can be used to detect whether thesensor beams are propagated through air, water, buildings, foliage, orother mediums (or combination of mediums). Once the propagation mediumis known, a suitable propagation frequency can be determined. If thewaveforms are propagated through a combination of mediums, controller124 can include logic to determine the most suitable frequency, orweighted average of propagation frequencies to use.

Process 806 can include amplifying the number of entangled quanta usedin the sensor beam required to achieve the desired resolution frequency.Process 806 can increase the number of quanta, but the frequency of thequanta will be lowered by a factor proportional to the increased number.Thus, changing the resolution frequency has little or no effect on thepropagation frequency since the propagation frequency is the sum of thefrequencies of the individual quantum.

Process 808 can include applying topological order to the waveformgenerated in process 806. The topological waveform can encodeinformation in configurations of different braids, which are similar toknots but consist of several different threads intertwined around eachother. By encoding waveforms in braids instead of single particles, atopological quantum waveform generator encodes the quanta in phaserelations. Further, the waveform can be represented redundantly so thaterrors can be diagnosed and corrected if the phase relations aredisrupted during propagation and/or processing. Further, entanglementrenormalization transformations can be used to reduce the amount ofentanglement in the waveforms.

Process 810 includes transmitting the entangled quanta waveform in aradio-frequency signal, which is typically accomplished using antenna106.

Process 812 includes receiving and detecting at least a portion of theentangled quanta reflected by a target. In some embodiments, process 814can separate one or more quanta from the return signal by passing thereturn signal through a beam splitter. The return signal can passthrough a series of beam splitters, and a single attribute orcharacteristic can be measured from each of the split signals. Note thatmeasuring a particular attribute of an entangled quanta will change theattribute. Process 812 thus allows each attributes/characteristics ofinterest to be measured without disturbing or changing the otherattributes/characteristics.

Process 816 can perform one or more techniques to condition the returnsignal for further processing. In some embodiments, one or more filterscan be used to remove noise components from the return signal.Alternatively or additionally, one or more amplifiers can be used toincrease desired frequencies or other properties of the return signal.Other suitable conditioning techniques to facilitate gatheringinformation from the return signal can be utilized in process 814.

Process 818 includes determining a characteristic of the target based oninteraction between the target and the entangled quanta. For example,the direction of a radar target's velocity vector can be determined fromthe polarization of the quanta in the return signal. The level of spincan be used to determine the magnitude of the target's velocity vector.The phase angle can be used to determine azimuth and elevation of thetarget, as well as the Doppler shift of the return signal. Spectralanalysis can be used to determine the material composition of thetarget. Information from other measured attributes of the quanta in thereturn signal can be determined in process 818.

While the present disclosure describes various embodiments, theseembodiments are to be understood as illustrative and do not limit theclaim scope. Many variations, modifications, additions and improvementsof the described embodiments are possible. For example, those havingordinary skill in the art will readily implement the processes necessaryto provide the structures and methods disclosed herein. Variations andmodifications of the embodiments disclosed herein may also be made whileremaining within the scope of the following claims. The functionalityand combinations of functionality of the individual modules can be anyappropriate functionality. Additionally, limitations set forth inpublications incorporated by reference herein are not intended to limitthe scope of the claims. In the claims, unless otherwise indicated thearticle “a” is to refer to “one or more than one”.

1. A sensor system comprising: an entangled quantum generator operableto generate a signal including a plurality of entangled quanta, thewavelength of the signal is the sum of the wavelengths of the pluralityof entangled quanta; a quantum detector configured to detect a returnsignal based on the signal being reflected by a target; and anattribute-specific detection device configured to determine acharacteristic of the target based on information derived from at leastone of the plurality of entangled quanta in the return signal, thefrequency of the signal is selected to propagate the signal through amedium and the frequencies of the plurality of entangled quanta isselected so that the characteristic of the target can be resolved fromthe return signal.
 2. The apparatus of claim 1, further comprising thecharacteristic of the target includes at least one of the groupconsisting of: location, speed, direction of travel, distance to target,target image, target size, target area, target volume, targetdimension(s), target cross-section, target surface roughness, and targetmaterial composition.
 3. The apparatus of claim 1, further comprisingthe entangled quantum generator is operable to vary the frequencies ofthe plurality of entangled quanta.
 4. The apparatus of claim 1, furthercomprising the entangled quantum generator utilizes at least one of thegroup consisting of: a photonic module, quantum dots, Bose-Einsteincondensates, and an atom cavity, to generate the entangled quanta. 5.The apparatus of claim 1, further comprising the entangled quantumgenerator is operable to vary the number of the plurality of entangledquanta included in the signal.
 6. The apparatus of claim 1, furthercomprising: the entangled quanta are topologically ordered.
 7. Theapparatus of claim 1, further comprising: a signal quality processorconfigured to receive a signal representing the return signal and toremove noise from the return signal.
 8. The apparatus of claim 1,further comprising an interferometric topological.
 9. The apparatus ofclaim 1, further comprising a positioning system operable to steer anantenna to radiate the signal in a desired direction and/or to detectthe return signal from a desired direction.
 10. The apparatus of claim1, further comprising a duplexer configured to switch operation betweentransmitting the signal and receiving the return signal.
 11. Theapparatus of claim 1, further comprising the signal/data processor isoperable to determine distance to the target based the time the signalis emitted and the return signal is detected.
 12. The apparatus of claim1, further comprising a beam splitter configured to separate at leastone quanta from the return signal and provide the at least one quanta tothe attribute-specific detection device.
 13. The apparatus of claim 1,further comprising a detector operable to detect at least one of theentangled quanta in the return signal.
 14. The apparatus of claim 1,further comprising a plurality of attribute-specific detection devicesand a series of beam splitters, the beam splitters are configured toseparate at least one quanta from the return signal and provide the atleast one quanta to a corresponding one of the attribute-specificdetection devices.
 15. The apparatus of claim 1, further comprising theentangled quanta are topologically ordered and renormalized.
 16. Amethod comprising: generating a plurality of entangled quanta;transmitting the entangled quanta in a radio-frequency signal, whereinthe frequency of the signal is selected to propagate through aparticular medium and the number of the entangled quanta is determinedby the selected frequency of the signal; and detecting at least aportion of the entangled quanta reflected by a target.
 17. The method ofclaim 16, further comprising: selecting the frequency of the transmittedentangled quanta to optimize target resolution achievable by detectingthe entangled quanta reflected by the target.
 18. The method of claim16, further comprising: selecting an attribute of the quanta to beentangled based on a characteristic of the target to be detected. 19.The method of claim 16, further comprising: determining a characteristicof the target based on interaction between the target and the entangledquanta.
 20. The method of claim 16, further comprising: compensating theinformation available from one of the entangled quanta based on thedifference in time between the one of the entangled quanta and anotherof the entangled quanta.
 21. The method of claim 16, further comprising:topologically ordering and renormalizing the entangled quanta.
 22. Anapparatus comprising: means for generating a plurality of entangledquanta; means for applying topological order and renormalization to theentangle quanta; and means for transmitting the entangled quanta in aradio-frequency signal, the frequency of the quanta is selected based onthe target to be detected and the number of entangled quanta is based onthe medium through which the entangled quanta will propagate.